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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Copyright (C) 2010 Zhenya Leonov<a name="line.2"></a>
<span class="sourceLineNo">003</span> *<a name="line.3"></a>
<span class="sourceLineNo">004</span> * Licensed under the Apache License, Version 2.0 (the "License");<a name="line.4"></a>
<span class="sourceLineNo">005</span> * you may not use this file except in compliance with the License.<a name="line.5"></a>
<span class="sourceLineNo">006</span> * You may obtain a copy of the License at<a name="line.6"></a>
<span class="sourceLineNo">007</span> *<a name="line.7"></a>
<span class="sourceLineNo">008</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.8"></a>
<span class="sourceLineNo">009</span> *<a name="line.9"></a>
<span class="sourceLineNo">010</span> * Unless required by applicable law or agreed to in writing, software<a name="line.10"></a>
<span class="sourceLineNo">011</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.11"></a>
<span class="sourceLineNo">012</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.12"></a>
<span class="sourceLineNo">013</span> * See the License for the specific language governing permissions and<a name="line.13"></a>
<span class="sourceLineNo">014</span> * limitations under the License.<a name="line.14"></a>
<span class="sourceLineNo">015</span> */<a name="line.15"></a>
<span class="sourceLineNo">016</span><a name="line.16"></a>
<span class="sourceLineNo">017</span>package com.palamida.util.collect;<a name="line.17"></a>
<span class="sourceLineNo">018</span><a name="line.18"></a>
<span class="sourceLineNo">019</span>import static com.google.common.base.Preconditions.checkNotNull;<a name="line.19"></a>
<span class="sourceLineNo">020</span><a name="line.20"></a>
<span class="sourceLineNo">021</span>import java.util.Collection;<a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.util.Deque;<a name="line.22"></a>
<span class="sourceLineNo">023</span>import java.util.Iterator;<a name="line.23"></a>
<span class="sourceLineNo">024</span>import java.util.List;<a name="line.24"></a>
<span class="sourceLineNo">025</span>import java.util.ListIterator;<a name="line.25"></a>
<span class="sourceLineNo">026</span>import java.util.NavigableSet;<a name="line.26"></a>
<span class="sourceLineNo">027</span>import java.util.NoSuchElementException;<a name="line.27"></a>
<span class="sourceLineNo">028</span><a name="line.28"></a>
<span class="sourceLineNo">029</span>import com.google.common.base.Function;<a name="line.29"></a>
<span class="sourceLineNo">030</span>import com.google.common.base.Predicate;<a name="line.30"></a>
<span class="sourceLineNo">031</span>import com.google.common.base.Predicates;<a name="line.31"></a>
<span class="sourceLineNo">032</span>import com.google.common.collect.ForwardingListIterator;<a name="line.32"></a>
<span class="sourceLineNo">033</span>import com.google.common.collect.Iterators;<a name="line.33"></a>
<span class="sourceLineNo">034</span>import com.google.common.collect.Lists;<a name="line.34"></a>
<span class="sourceLineNo">035</span>import com.google.common.collect.PeekingIterator;<a name="line.35"></a>
<span class="sourceLineNo">036</span>import com.google.common.collect.UnmodifiableIterator;<a name="line.36"></a>
<span class="sourceLineNo">037</span><a name="line.37"></a>
<span class="sourceLineNo">038</span>/**<a name="line.38"></a>
<span class="sourceLineNo">039</span> * Static utility methods which operate on or return {@link Iterator}s.<a name="line.39"></a>
<span class="sourceLineNo">040</span> * <a name="line.40"></a>
<span class="sourceLineNo">041</span> * @author Zhenya Leonov<a name="line.41"></a>
<span class="sourceLineNo">042</span> * @see Iterators<a name="line.42"></a>
<span class="sourceLineNo">043</span> */<a name="line.43"></a>
<span class="sourceLineNo">044</span>public final class MoreIterators {<a name="line.44"></a>
<span class="sourceLineNo">045</span><a name="line.45"></a>
<span class="sourceLineNo">046</span>        private MoreIterators() {<a name="line.46"></a>
<span class="sourceLineNo">047</span>        }<a name="line.47"></a>
<span class="sourceLineNo">048</span><a name="line.48"></a>
<span class="sourceLineNo">049</span>        private static final ListIterator&lt;Object&gt; EMPTY_LIST_ITERATOR = new EmptyListIterator&lt;Object&gt;();<a name="line.49"></a>
<span class="sourceLineNo">050</span>        private static final PeekingIterator&lt;Object&gt; EMPTY_PEEKING_ITERATOR = new EmptyPeekingIterator&lt;Object&gt;();<a name="line.50"></a>
<span class="sourceLineNo">051</span><a name="line.51"></a>
<span class="sourceLineNo">052</span>        /**<a name="line.52"></a>
<span class="sourceLineNo">053</span>         * Combines multiple list iterators into a single {@code ListIterator}. The<a name="line.53"></a>
<span class="sourceLineNo">054</span>         * returned list iterator supports the {@code add(E)}, {@code remove()}, and<a name="line.54"></a>
<span class="sourceLineNo">055</span>         * {@code set(E)} operations if the corresponding backing iterator supports<a name="line.55"></a>
<span class="sourceLineNo">056</span>         * them.<a name="line.56"></a>
<span class="sourceLineNo">057</span>         * <a name="line.57"></a>
<span class="sourceLineNo">058</span>         * @param inputs<a name="line.58"></a>
<span class="sourceLineNo">059</span>         *            the source list iterators<a name="line.59"></a>
<span class="sourceLineNo">060</span>         * @return a {@code ListIterator} consisting of specified list iterators<a name="line.60"></a>
<span class="sourceLineNo">061</span>         */<a name="line.61"></a>
<span class="sourceLineNo">062</span>        public static &lt;E&gt; ListIterator&lt;E&gt; concat(final ListIterator&lt;E&gt;... inputs) {<a name="line.62"></a>
<span class="sourceLineNo">063</span>                checkNotNull(inputs);<a name="line.63"></a>
<span class="sourceLineNo">064</span>                for (ListIterator&lt;E&gt; li : inputs)<a name="line.64"></a>
<span class="sourceLineNo">065</span>                        checkNotNull(li);<a name="line.65"></a>
<span class="sourceLineNo">066</span>                return new ListIterator&lt;E&gt;() {<a name="line.66"></a>
<span class="sourceLineNo">067</span>                        private int count = 0;<a name="line.67"></a>
<span class="sourceLineNo">068</span>                        private int index = 0;<a name="line.68"></a>
<span class="sourceLineNo">069</span><a name="line.69"></a>
<span class="sourceLineNo">070</span>                        @Override<a name="line.70"></a>
<span class="sourceLineNo">071</span>                        public void add(E e) {<a name="line.71"></a>
<span class="sourceLineNo">072</span>                                inputs[count].add(e);<a name="line.72"></a>
<span class="sourceLineNo">073</span>                        }<a name="line.73"></a>
<span class="sourceLineNo">074</span><a name="line.74"></a>
<span class="sourceLineNo">075</span>                        @Override<a name="line.75"></a>
<span class="sourceLineNo">076</span>                        public boolean hasNext() {<a name="line.76"></a>
<span class="sourceLineNo">077</span>                                while (count &lt; inputs.length) {<a name="line.77"></a>
<span class="sourceLineNo">078</span>                                        if (inputs[count].hasNext())<a name="line.78"></a>
<span class="sourceLineNo">079</span>                                                return true;<a name="line.79"></a>
<span class="sourceLineNo">080</span>                                        count++;<a name="line.80"></a>
<span class="sourceLineNo">081</span>                                }<a name="line.81"></a>
<span class="sourceLineNo">082</span>                                count--;<a name="line.82"></a>
<span class="sourceLineNo">083</span>                                return false;<a name="line.83"></a>
<span class="sourceLineNo">084</span>                        }<a name="line.84"></a>
<span class="sourceLineNo">085</span><a name="line.85"></a>
<span class="sourceLineNo">086</span>                        @Override<a name="line.86"></a>
<span class="sourceLineNo">087</span>                        public boolean hasPrevious() {<a name="line.87"></a>
<span class="sourceLineNo">088</span>                                while (count &gt;= 0) {<a name="line.88"></a>
<span class="sourceLineNo">089</span>                                        if (inputs[count].hasPrevious())<a name="line.89"></a>
<span class="sourceLineNo">090</span>                                                return true;<a name="line.90"></a>
<span class="sourceLineNo">091</span>                                        count--;<a name="line.91"></a>
<span class="sourceLineNo">092</span>                                }<a name="line.92"></a>
<span class="sourceLineNo">093</span>                                count = 0;<a name="line.93"></a>
<span class="sourceLineNo">094</span>                                return false;<a name="line.94"></a>
<span class="sourceLineNo">095</span>                        }<a name="line.95"></a>
<span class="sourceLineNo">096</span><a name="line.96"></a>
<span class="sourceLineNo">097</span>                        @Override<a name="line.97"></a>
<span class="sourceLineNo">098</span>                        public E next() {<a name="line.98"></a>
<span class="sourceLineNo">099</span>                                if (hasNext()) {<a name="line.99"></a>
<span class="sourceLineNo">100</span>                                        index++;<a name="line.100"></a>
<span class="sourceLineNo">101</span>                                        return inputs[count].next();<a name="line.101"></a>
<span class="sourceLineNo">102</span>                                }<a name="line.102"></a>
<span class="sourceLineNo">103</span>                                throw new NoSuchElementException();<a name="line.103"></a>
<span class="sourceLineNo">104</span>                        }<a name="line.104"></a>
<span class="sourceLineNo">105</span><a name="line.105"></a>
<span class="sourceLineNo">106</span>                        @Override<a name="line.106"></a>
<span class="sourceLineNo">107</span>                        public int nextIndex() {<a name="line.107"></a>
<span class="sourceLineNo">108</span>                                return index;<a name="line.108"></a>
<span class="sourceLineNo">109</span>                        }<a name="line.109"></a>
<span class="sourceLineNo">110</span><a name="line.110"></a>
<span class="sourceLineNo">111</span>                        @Override<a name="line.111"></a>
<span class="sourceLineNo">112</span>                        public E previous() {<a name="line.112"></a>
<span class="sourceLineNo">113</span>                                if (hasPrevious()) {<a name="line.113"></a>
<span class="sourceLineNo">114</span>                                        index--;<a name="line.114"></a>
<span class="sourceLineNo">115</span>                                        return inputs[count].previous();<a name="line.115"></a>
<span class="sourceLineNo">116</span>                                }<a name="line.116"></a>
<span class="sourceLineNo">117</span>                                throw new NoSuchElementException();<a name="line.117"></a>
<span class="sourceLineNo">118</span>                        }<a name="line.118"></a>
<span class="sourceLineNo">119</span><a name="line.119"></a>
<span class="sourceLineNo">120</span>                        @Override<a name="line.120"></a>
<span class="sourceLineNo">121</span>                        public int previousIndex() {<a name="line.121"></a>
<span class="sourceLineNo">122</span>                                return index - 1;<a name="line.122"></a>
<span class="sourceLineNo">123</span>                        }<a name="line.123"></a>
<span class="sourceLineNo">124</span><a name="line.124"></a>
<span class="sourceLineNo">125</span>                        @Override<a name="line.125"></a>
<span class="sourceLineNo">126</span>                        public void remove() {<a name="line.126"></a>
<span class="sourceLineNo">127</span>                                inputs[count].remove();<a name="line.127"></a>
<span class="sourceLineNo">128</span>                        }<a name="line.128"></a>
<span class="sourceLineNo">129</span><a name="line.129"></a>
<span class="sourceLineNo">130</span>                        @Override<a name="line.130"></a>
<span class="sourceLineNo">131</span>                        public void set(E e) {<a name="line.131"></a>
<span class="sourceLineNo">132</span>                                inputs[count].set(e);<a name="line.132"></a>
<span class="sourceLineNo">133</span>                        }<a name="line.133"></a>
<span class="sourceLineNo">134</span>                };<a name="line.134"></a>
<span class="sourceLineNo">135</span>        }<a name="line.135"></a>
<span class="sourceLineNo">136</span><a name="line.136"></a>
<span class="sourceLineNo">137</span>        /**<a name="line.137"></a>
<span class="sourceLineNo">138</span>         * Decorates the given {@code ListIterator} to return only the elements that<a name="line.138"></a>
<span class="sourceLineNo">139</span>         * are instances of the specified {@code Class}.<a name="line.139"></a>
<span class="sourceLineNo">140</span>         * <a name="line.140"></a>
<span class="sourceLineNo">141</span>         * @param unfiltered<a name="line.141"></a>
<span class="sourceLineNo">142</span>         *            a list iterator containing objects of any type<a name="line.142"></a>
<span class="sourceLineNo">143</span>         * @param type<a name="line.143"></a>
<span class="sourceLineNo">144</span>         *            the type of elements desired<a name="line.144"></a>
<span class="sourceLineNo">145</span>         * @return an {@code UnmodifiableListIterator} containing all elements of<a name="line.145"></a>
<span class="sourceLineNo">146</span>         *         the original iterator that were of the requested type<a name="line.146"></a>
<span class="sourceLineNo">147</span>         */<a name="line.147"></a>
<span class="sourceLineNo">148</span>        public static &lt;E&gt; UnmodifiableListIterator&lt;E&gt; filter(<a name="line.148"></a>
<span class="sourceLineNo">149</span>                        final ListIterator&lt;E&gt; unfiltered, final Class&lt;E&gt; type) {<a name="line.149"></a>
<span class="sourceLineNo">150</span>                return filter(unfiltered, Predicates.instanceOf(type));<a name="line.150"></a>
<span class="sourceLineNo">151</span>        }<a name="line.151"></a>
<span class="sourceLineNo">152</span><a name="line.152"></a>
<span class="sourceLineNo">153</span>        /**<a name="line.153"></a>
<span class="sourceLineNo">154</span>         * Decorates the given {@code ListIterator} to return only the elements that<a name="line.154"></a>
<span class="sourceLineNo">155</span>         * satisfy the specified {@code Predicate}.<a name="line.155"></a>
<span class="sourceLineNo">156</span>         * <a name="line.156"></a>
<span class="sourceLineNo">157</span>         * @param unfiltered<a name="line.157"></a>
<span class="sourceLineNo">158</span>         *            the given list iterator<a name="line.158"></a>
<span class="sourceLineNo">159</span>         * @param predicate<a name="line.159"></a>
<span class="sourceLineNo">160</span>         *            the specified predicate<a name="line.160"></a>
<span class="sourceLineNo">161</span>         * @return an {@code UnmodifiableListIterator} which returns only the<a name="line.161"></a>
<span class="sourceLineNo">162</span>         *         elements of {@code unfiltered} that satisfy {@code predicate}<a name="line.162"></a>
<span class="sourceLineNo">163</span>         */<a name="line.163"></a>
<span class="sourceLineNo">164</span>        public static &lt;E&gt; UnmodifiableListIterator&lt;E&gt; filter(<a name="line.164"></a>
<span class="sourceLineNo">165</span>                        final ListIterator&lt;E&gt; unfiltered,<a name="line.165"></a>
<span class="sourceLineNo">166</span>                        final Predicate&lt;? super E&gt; predicate) {<a name="line.166"></a>
<span class="sourceLineNo">167</span>                checkNotNull(unfiltered);<a name="line.167"></a>
<span class="sourceLineNo">168</span>                checkNotNull(predicate);<a name="line.168"></a>
<span class="sourceLineNo">169</span>                return new UnmodifiableListIterator&lt;E&gt;() {<a name="line.169"></a>
<span class="sourceLineNo">170</span>                        private E nextElement;<a name="line.170"></a>
<span class="sourceLineNo">171</span>                        private E prevElement;<a name="line.171"></a>
<span class="sourceLineNo">172</span>                        private int index = 0;<a name="line.172"></a>
<span class="sourceLineNo">173</span>                        private boolean hasNext;<a name="line.173"></a>
<span class="sourceLineNo">174</span>                        private boolean hasPrev;<a name="line.174"></a>
<span class="sourceLineNo">175</span>                        private boolean next = false;<a name="line.175"></a>
<span class="sourceLineNo">176</span>                        private boolean prev = false;<a name="line.176"></a>
<span class="sourceLineNo">177</span><a name="line.177"></a>
<span class="sourceLineNo">178</span>                        @Override<a name="line.178"></a>
<span class="sourceLineNo">179</span>                        public boolean hasNext() {<a name="line.179"></a>
<span class="sourceLineNo">180</span>                                if (next &amp;&amp; hasNext)<a name="line.180"></a>
<span class="sourceLineNo">181</span>                                        return true;<a name="line.181"></a>
<span class="sourceLineNo">182</span>                                prev = false;<a name="line.182"></a>
<span class="sourceLineNo">183</span>                                while (delegate().hasNext()) {<a name="line.183"></a>
<span class="sourceLineNo">184</span>                                        nextElement = delegate().next();<a name="line.184"></a>
<span class="sourceLineNo">185</span>                                        if (predicate.apply(nextElement))<a name="line.185"></a>
<span class="sourceLineNo">186</span>                                                return next = hasNext = true;<a name="line.186"></a>
<span class="sourceLineNo">187</span>                                }<a name="line.187"></a>
<span class="sourceLineNo">188</span>                                return false;<a name="line.188"></a>
<span class="sourceLineNo">189</span>                        }<a name="line.189"></a>
<span class="sourceLineNo">190</span><a name="line.190"></a>
<span class="sourceLineNo">191</span>                        @Override<a name="line.191"></a>
<span class="sourceLineNo">192</span>                        public boolean hasPrevious() {<a name="line.192"></a>
<span class="sourceLineNo">193</span>                                if (prev &amp;&amp; hasPrev)<a name="line.193"></a>
<span class="sourceLineNo">194</span>                                        return true;<a name="line.194"></a>
<span class="sourceLineNo">195</span>                                next = false;<a name="line.195"></a>
<span class="sourceLineNo">196</span>                                while (delegate().hasPrevious()) {<a name="line.196"></a>
<span class="sourceLineNo">197</span>                                        prevElement = delegate().previous();<a name="line.197"></a>
<span class="sourceLineNo">198</span>                                        if (predicate.apply(prevElement))<a name="line.198"></a>
<span class="sourceLineNo">199</span>                                                return prev = hasPrev = true;<a name="line.199"></a>
<span class="sourceLineNo">200</span>                                }<a name="line.200"></a>
<span class="sourceLineNo">201</span>                                return false;<a name="line.201"></a>
<span class="sourceLineNo">202</span>                        }<a name="line.202"></a>
<span class="sourceLineNo">203</span><a name="line.203"></a>
<span class="sourceLineNo">204</span>                        @Override<a name="line.204"></a>
<span class="sourceLineNo">205</span>                        public E next() {<a name="line.205"></a>
<span class="sourceLineNo">206</span>                                if (!next)<a name="line.206"></a>
<span class="sourceLineNo">207</span>                                        hasNext();<a name="line.207"></a>
<span class="sourceLineNo">208</span>                                if (hasNext) {<a name="line.208"></a>
<span class="sourceLineNo">209</span>                                        index++;<a name="line.209"></a>
<span class="sourceLineNo">210</span>                                        next = false;<a name="line.210"></a>
<span class="sourceLineNo">211</span>                                        return nextElement;<a name="line.211"></a>
<span class="sourceLineNo">212</span>                                } else<a name="line.212"></a>
<span class="sourceLineNo">213</span>                                        throw new NoSuchElementException();<a name="line.213"></a>
<span class="sourceLineNo">214</span>                        }<a name="line.214"></a>
<span class="sourceLineNo">215</span><a name="line.215"></a>
<span class="sourceLineNo">216</span>                        @Override<a name="line.216"></a>
<span class="sourceLineNo">217</span>                        public int nextIndex() {<a name="line.217"></a>
<span class="sourceLineNo">218</span>                                return index;<a name="line.218"></a>
<span class="sourceLineNo">219</span>                        }<a name="line.219"></a>
<span class="sourceLineNo">220</span><a name="line.220"></a>
<span class="sourceLineNo">221</span>                        @Override<a name="line.221"></a>
<span class="sourceLineNo">222</span>                        public E previous() {<a name="line.222"></a>
<span class="sourceLineNo">223</span>                                if (!prev)<a name="line.223"></a>
<span class="sourceLineNo">224</span>                                        hasPrevious();<a name="line.224"></a>
<span class="sourceLineNo">225</span>                                if (hasPrev) {<a name="line.225"></a>
<span class="sourceLineNo">226</span>                                        index--;<a name="line.226"></a>
<span class="sourceLineNo">227</span>                                        prev = false;<a name="line.227"></a>
<span class="sourceLineNo">228</span>                                        return prevElement;<a name="line.228"></a>
<span class="sourceLineNo">229</span>                                } else<a name="line.229"></a>
<span class="sourceLineNo">230</span>                                        throw new NoSuchElementException();<a name="line.230"></a>
<span class="sourceLineNo">231</span>                        }<a name="line.231"></a>
<span class="sourceLineNo">232</span><a name="line.232"></a>
<span class="sourceLineNo">233</span>                        @Override<a name="line.233"></a>
<span class="sourceLineNo">234</span>                        public int previousIndex() {<a name="line.234"></a>
<span class="sourceLineNo">235</span>                                return index - 1;<a name="line.235"></a>
<span class="sourceLineNo">236</span>                        }<a name="line.236"></a>
<span class="sourceLineNo">237</span><a name="line.237"></a>
<span class="sourceLineNo">238</span>                        @Override<a name="line.238"></a>
<span class="sourceLineNo">239</span>                        protected ListIterator&lt;E&gt; delegate() {<a name="line.239"></a>
<span class="sourceLineNo">240</span>                                return unfiltered;<a name="line.240"></a>
<span class="sourceLineNo">241</span>                        }<a name="line.241"></a>
<span class="sourceLineNo">242</span>                };<a name="line.242"></a>
<span class="sourceLineNo">243</span>        }<a name="line.243"></a>
<span class="sourceLineNo">244</span><a name="line.244"></a>
<span class="sourceLineNo">245</span>        /**<a name="line.245"></a>
<span class="sourceLineNo">246</span>         * Returns an immutable empty {@code ListIterator}.<a name="line.246"></a>
<span class="sourceLineNo">247</span>         * <a name="line.247"></a>
<span class="sourceLineNo">248</span>         * @return an immutable empty {@code ListIterator}<a name="line.248"></a>
<span class="sourceLineNo">249</span>         */<a name="line.249"></a>
<span class="sourceLineNo">250</span>        @SuppressWarnings("unchecked")<a name="line.250"></a>
<span class="sourceLineNo">251</span>        public static &lt;E&gt; ListIterator&lt;E&gt; emptyListIterator() {<a name="line.251"></a>
<span class="sourceLineNo">252</span>                return (ListIterator&lt;E&gt;) EMPTY_LIST_ITERATOR;<a name="line.252"></a>
<span class="sourceLineNo">253</span>        }<a name="line.253"></a>
<span class="sourceLineNo">254</span><a name="line.254"></a>
<span class="sourceLineNo">255</span>        /**<a name="line.255"></a>
<span class="sourceLineNo">256</span>         * Returns an immutable empty {@code PeekingIterator}.<a name="line.256"></a>
<span class="sourceLineNo">257</span>         * <a name="line.257"></a>
<span class="sourceLineNo">258</span>         * @return an immutable empty {@code PeekingIterator}<a name="line.258"></a>
<span class="sourceLineNo">259</span>         */<a name="line.259"></a>
<span class="sourceLineNo">260</span>        @SuppressWarnings("unchecked")<a name="line.260"></a>
<span class="sourceLineNo">261</span>        public static &lt;E&gt; PeekingIterator&lt;E&gt; emptyPeekingIterator() {<a name="line.261"></a>
<span class="sourceLineNo">262</span>                return (PeekingIterator&lt;E&gt;) EMPTY_PEEKING_ITERATOR;<a name="line.262"></a>
<span class="sourceLineNo">263</span>        }<a name="line.263"></a>
<span class="sourceLineNo">264</span><a name="line.264"></a>
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<span class="sourceLineNo">266</span>         * Decorates the specified {@code Iterator} to behave like a<a name="line.266"></a>
<span class="sourceLineNo">267</span>         * {@code ListIterator} by maintaining a {@code List} of all elements<a name="line.267"></a>
<span class="sourceLineNo">268</span>         * returned from calls to {@code next()}.<a name="line.268"></a>
<span class="sourceLineNo">269</span>         * &lt;p&gt;<a name="line.269"></a>
<span class="sourceLineNo">270</span>         * The {@code remove()}, {@code set(E)}, and {@code add(E)} operations are<a name="line.270"></a>
<span class="sourceLineNo">271</span>         * not supported. Modifying the underlying {@code Iterator} yields<a name="line.271"></a>
<span class="sourceLineNo">272</span>         * unpredictable results.<a name="line.272"></a>
<span class="sourceLineNo">273</span>         * <a name="line.273"></a>
<span class="sourceLineNo">274</span>         * @param iterator<a name="line.274"></a>
<span class="sourceLineNo">275</span>         *            the underlying {@code Iterator}<a name="line.275"></a>
<span class="sourceLineNo">276</span>         * @return a {@code UnmodifiableListIterator} backed by {@code iterator}<a name="line.276"></a>
<span class="sourceLineNo">277</span>         */<a name="line.277"></a>
<span class="sourceLineNo">278</span>        public static &lt;E&gt; UnmodifiableListIterator&lt;E&gt; listIterator(<a name="line.278"></a>
<span class="sourceLineNo">279</span>                        final Iterator&lt;E&gt; iterator) {<a name="line.279"></a>
<span class="sourceLineNo">280</span>                checkNotNull(iterator);<a name="line.280"></a>
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<span class="sourceLineNo">282</span>                        private final List&lt;E&gt; list = Lists.newArrayList();<a name="line.282"></a>
<span class="sourceLineNo">283</span>                        private int index = -1;<a name="line.283"></a>
<span class="sourceLineNo">284</span><a name="line.284"></a>
<span class="sourceLineNo">285</span>                        @Override<a name="line.285"></a>
<span class="sourceLineNo">286</span>                        public boolean hasNext() {<a name="line.286"></a>
<span class="sourceLineNo">287</span>                                if (index == list.size() - 1)<a name="line.287"></a>
<span class="sourceLineNo">288</span>                                        return iterator.hasNext();<a name="line.288"></a>
<span class="sourceLineNo">289</span>                                else<a name="line.289"></a>
<span class="sourceLineNo">290</span>                                        return true;<a name="line.290"></a>
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<span class="sourceLineNo">293</span>                        @Override<a name="line.293"></a>
<span class="sourceLineNo">294</span>                        public E next() {<a name="line.294"></a>
<span class="sourceLineNo">295</span>                                E nextElement;<a name="line.295"></a>
<span class="sourceLineNo">296</span>                                if (index == list.size() - 1) {<a name="line.296"></a>
<span class="sourceLineNo">297</span>                                        nextElement = iterator.next();<a name="line.297"></a>
<span class="sourceLineNo">298</span>                                        list.add(nextElement);<a name="line.298"></a>
<span class="sourceLineNo">299</span>                                        index++;<a name="line.299"></a>
<span class="sourceLineNo">300</span>                                } else<a name="line.300"></a>
<span class="sourceLineNo">301</span>                                        nextElement = list.get(++index);<a name="line.301"></a>
<span class="sourceLineNo">302</span>                                return nextElement;<a name="line.302"></a>
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<span class="sourceLineNo">305</span>                        @Override<a name="line.305"></a>
<span class="sourceLineNo">306</span>                        public boolean hasPrevious() {<a name="line.306"></a>
<span class="sourceLineNo">307</span>                                return index &gt;= 0;<a name="line.307"></a>
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<span class="sourceLineNo">309</span><a name="line.309"></a>
<span class="sourceLineNo">310</span>                        @Override<a name="line.310"></a>
<span class="sourceLineNo">311</span>                        public E previous() {<a name="line.311"></a>
<span class="sourceLineNo">312</span>                                if (index &lt; 0)<a name="line.312"></a>
<span class="sourceLineNo">313</span>                                        throw new NoSuchElementException();<a name="line.313"></a>
<span class="sourceLineNo">314</span>                                return list.get(index--);<a name="line.314"></a>
<span class="sourceLineNo">315</span>                        }<a name="line.315"></a>
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<span class="sourceLineNo">317</span>                        @Override<a name="line.317"></a>
<span class="sourceLineNo">318</span>                        public int nextIndex() {<a name="line.318"></a>
<span class="sourceLineNo">319</span>                                return index + 1;<a name="line.319"></a>
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<span class="sourceLineNo">322</span>                        @Override<a name="line.322"></a>
<span class="sourceLineNo">323</span>                        public int previousIndex() {<a name="line.323"></a>
<span class="sourceLineNo">324</span>                                return index;<a name="line.324"></a>
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<span class="sourceLineNo">327</span>                        // This method is never used.<a name="line.327"></a>
<span class="sourceLineNo">328</span>                        @Override<a name="line.328"></a>
<span class="sourceLineNo">329</span>                        protected ListIterator&lt;E&gt; delegate() {<a name="line.329"></a>
<span class="sourceLineNo">330</span>                                return this;<a name="line.330"></a>
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<span class="sourceLineNo">332</span>                };<a name="line.332"></a>
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<span class="sourceLineNo">335</span>        /**<a name="line.335"></a>
<span class="sourceLineNo">336</span>         * Returns an {@code Iterator} over the specified {@code Collection} in<a name="line.336"></a>
<span class="sourceLineNo">337</span>         * reverse sequential order. If the specified collection is an instance of<a name="line.337"></a>
<span class="sourceLineNo">338</span>         * {@code Deque} or {@code NavigableSet} the iterator is obtained by<a name="line.338"></a>
<span class="sourceLineNo">339</span>         * invoking the {@code descendingIterator()} method, else an unmodifiable<a name="line.339"></a>
<span class="sourceLineNo">340</span>         * iterator is returned by calling the {@code reverseOrder(Iterator)}<a name="line.340"></a>
<span class="sourceLineNo">341</span>         * method.<a name="line.341"></a>
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<span class="sourceLineNo">343</span>         * @param c<a name="line.343"></a>
<span class="sourceLineNo">344</span>         *            the specified collection<a name="line.344"></a>
<span class="sourceLineNo">345</span>         * @return an iterator over the specified collection in reverse sequential<a name="line.345"></a>
<span class="sourceLineNo">346</span>         *         order<a name="line.346"></a>
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<span class="sourceLineNo">349</span>        public static &lt;E&gt; Iterator&lt;E&gt; reverseOrder(final Collection&lt;? extends E&gt; c) {<a name="line.349"></a>
<span class="sourceLineNo">350</span>                checkNotNull(c);<a name="line.350"></a>
<span class="sourceLineNo">351</span>                if (c instanceof Deque&lt;?&gt;)<a name="line.351"></a>
<span class="sourceLineNo">352</span>                        return ((Deque) c).descendingIterator();<a name="line.352"></a>
<span class="sourceLineNo">353</span>                if (c instanceof NavigableSet&lt;?&gt;)<a name="line.353"></a>
<span class="sourceLineNo">354</span>                        return ((NavigableSet) c).descendingIterator();<a name="line.354"></a>
<span class="sourceLineNo">355</span>                else<a name="line.355"></a>
<span class="sourceLineNo">356</span>                        return reverseOrder(c.iterator());<a name="line.356"></a>
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<span class="sourceLineNo">360</span>        /**<a name="line.360"></a>
<span class="sourceLineNo">361</span>         * Returns an {@code UnmodifiableIterator} which reverses the iteration<a name="line.361"></a>
<span class="sourceLineNo">362</span>         * order of the specified {@code Iterator}. The underlying iterator must be<a name="line.362"></a>
<span class="sourceLineNo">363</span>         * non-blocking and finite, because it is necessary to iterate through all<a name="line.363"></a>
<span class="sourceLineNo">364</span>         * its elements on startup.<a name="line.364"></a>
<span class="sourceLineNo">365</span>         * <a name="line.365"></a>
<span class="sourceLineNo">366</span>         * @param iterator<a name="line.366"></a>
<span class="sourceLineNo">367</span>         *            the underlying {@code Iterator}<a name="line.367"></a>
<span class="sourceLineNo">368</span>         * @return a reverse view of {@code iterator}<a name="line.368"></a>
<span class="sourceLineNo">369</span>         */<a name="line.369"></a>
<span class="sourceLineNo">370</span>        public static &lt;E&gt; UnmodifiableIterator&lt;E&gt; reverseOrder(<a name="line.370"></a>
<span class="sourceLineNo">371</span>                        final Iterator&lt;? extends E&gt; iterator) {<a name="line.371"></a>
<span class="sourceLineNo">372</span>                checkNotNull(iterator);<a name="line.372"></a>
<span class="sourceLineNo">373</span>                final Deque&lt;E&gt; stack = Lists.newLinkedList();<a name="line.373"></a>
<span class="sourceLineNo">374</span>                while (iterator.hasNext()) {<a name="line.374"></a>
<span class="sourceLineNo">375</span>                        stack.push(iterator.next());<a name="line.375"></a>
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<span class="sourceLineNo">377</span>                return new UnmodifiableIterator&lt;E&gt;() {<a name="line.377"></a>
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<span class="sourceLineNo">379</span>                        public boolean hasNext() {<a name="line.379"></a>
<span class="sourceLineNo">380</span>                                return !stack.isEmpty();<a name="line.380"></a>
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<span class="sourceLineNo">382</span><a name="line.382"></a>
<span class="sourceLineNo">383</span>                        @Override<a name="line.383"></a>
<span class="sourceLineNo">384</span>                        public E next() {<a name="line.384"></a>
<span class="sourceLineNo">385</span>                                return stack.pop();<a name="line.385"></a>
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<span class="sourceLineNo">387</span>                };<a name="line.387"></a>
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<span class="sourceLineNo">390</span>        /**<a name="line.390"></a>
<span class="sourceLineNo">391</span>         * Returns a {@code ListIterator} that applies the specified<a name="line.391"></a>
<span class="sourceLineNo">392</span>         * {@code Function} to each element of the given list iterator.<a name="line.392"></a>
<span class="sourceLineNo">393</span>         * &lt;p&gt;<a name="line.393"></a>
<span class="sourceLineNo">394</span>         * The returned list iterator does not support {@code add(E)} and<a name="line.394"></a>
<span class="sourceLineNo">395</span>         * {@code set(E)} but does support {@code remove()} if the given list<a name="line.395"></a>
<span class="sourceLineNo">396</span>         * iterator does.<a name="line.396"></a>
<span class="sourceLineNo">397</span>         * <a name="line.397"></a>
<span class="sourceLineNo">398</span>         * @param &lt;E&gt;<a name="line.398"></a>
<span class="sourceLineNo">399</span>         *            the type of elements traversed by the given list iterator<a name="line.399"></a>
<span class="sourceLineNo">400</span>         * @param &lt;T&gt;<a name="line.400"></a>
<span class="sourceLineNo">401</span>         *            the type of output of the specified function<a name="line.401"></a>
<span class="sourceLineNo">402</span>         * @param fromIterator<a name="line.402"></a>
<span class="sourceLineNo">403</span>         *            the given list iterator<a name="line.403"></a>
<span class="sourceLineNo">404</span>         * @param function<a name="line.404"></a>
<span class="sourceLineNo">405</span>         *            the specified function<a name="line.405"></a>
<span class="sourceLineNo">406</span>         * @return a list iterator that applies {@code function} to each element of<a name="line.406"></a>
<span class="sourceLineNo">407</span>         *         {@code fromIterator}<a name="line.407"></a>
<span class="sourceLineNo">408</span>         */<a name="line.408"></a>
<span class="sourceLineNo">409</span>        public static &lt;E, T&gt; ListIterator&lt;T&gt; transform(<a name="line.409"></a>
<span class="sourceLineNo">410</span>                        final ListIterator&lt;E&gt; fromIterator,<a name="line.410"></a>
<span class="sourceLineNo">411</span>                        final Function&lt;? super E, ? extends T&gt; function) {<a name="line.411"></a>
<span class="sourceLineNo">412</span>                checkNotNull(fromIterator);<a name="line.412"></a>
<span class="sourceLineNo">413</span>                checkNotNull(function);<a name="line.413"></a>
<span class="sourceLineNo">414</span>                return new ForwardingListIterator&lt;T&gt;() {<a name="line.414"></a>
<span class="sourceLineNo">415</span>                        @Override<a name="line.415"></a>
<span class="sourceLineNo">416</span>                        public T next() {<a name="line.416"></a>
<span class="sourceLineNo">417</span>                                return function.apply(fromIterator.next());<a name="line.417"></a>
<span class="sourceLineNo">418</span>                        }<a name="line.418"></a>
<span class="sourceLineNo">419</span><a name="line.419"></a>
<span class="sourceLineNo">420</span>                        @Override<a name="line.420"></a>
<span class="sourceLineNo">421</span>                        public void add(T e) {<a name="line.421"></a>
<span class="sourceLineNo">422</span>                                throw new UnsupportedOperationException();<a name="line.422"></a>
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<span class="sourceLineNo">424</span><a name="line.424"></a>
<span class="sourceLineNo">425</span>                        @Override<a name="line.425"></a>
<span class="sourceLineNo">426</span>                        public T previous() {<a name="line.426"></a>
<span class="sourceLineNo">427</span>                                return function.apply(fromIterator.previous());<a name="line.427"></a>
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<span class="sourceLineNo">429</span><a name="line.429"></a>
<span class="sourceLineNo">430</span>                        @Override<a name="line.430"></a>
<span class="sourceLineNo">431</span>                        public void set(T e) {<a name="line.431"></a>
<span class="sourceLineNo">432</span>                                throw new UnsupportedOperationException();<a name="line.432"></a>
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<span class="sourceLineNo">434</span>                <a name="line.434"></a>
<span class="sourceLineNo">435</span>                        @SuppressWarnings("unchecked")<a name="line.435"></a>
<span class="sourceLineNo">436</span>                        @Override<a name="line.436"></a>
<span class="sourceLineNo">437</span>                        // ok since type T is only used in next, previous, add, and set<a name="line.437"></a>
<span class="sourceLineNo">438</span>                        protected ListIterator&lt;T&gt; delegate() {<a name="line.438"></a>
<span class="sourceLineNo">439</span>                                return (ListIterator&lt;T&gt;) fromIterator;<a name="line.439"></a>
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<span class="sourceLineNo">441</span>                };<a name="line.441"></a>
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<span class="sourceLineNo">443</span><a name="line.443"></a>
<span class="sourceLineNo">444</span>        /**<a name="line.444"></a>
<span class="sourceLineNo">445</span>         * Decorates the specified {@code ListIterator} to prevent {@code remove()},<a name="line.445"></a>
<span class="sourceLineNo">446</span>         * {@code add(E)}, and {@code set(E)}.<a name="line.446"></a>
<span class="sourceLineNo">447</span>         * <a name="line.447"></a>
<span class="sourceLineNo">448</span>         * @param listIterator<a name="line.448"></a>
<span class="sourceLineNo">449</span>         *            the underlying {@code ListIterator}<a name="line.449"></a>
<span class="sourceLineNo">450</span>         * @return an unmodifiable view of {@code listIterator}<a name="line.450"></a>
<span class="sourceLineNo">451</span>         */<a name="line.451"></a>
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<span class="sourceLineNo">453</span>                        final ListIterator&lt;? extends E&gt; listIterator) {<a name="line.453"></a>
<span class="sourceLineNo">454</span>                checkNotNull(listIterator);<a name="line.454"></a>
<span class="sourceLineNo">455</span>                return new UnmodifiableListIterator&lt;E&gt;() {<a name="line.455"></a>
<span class="sourceLineNo">456</span>                        @SuppressWarnings("unchecked")<a name="line.456"></a>
<span class="sourceLineNo">457</span>                        @Override<a name="line.457"></a>
<span class="sourceLineNo">458</span>                        protected ListIterator&lt;E&gt; delegate() {<a name="line.458"></a>
<span class="sourceLineNo">459</span>                                return (ListIterator&lt;E&gt;) listIterator;<a name="line.459"></a>
<span class="sourceLineNo">460</span>                        }<a name="line.460"></a>
<span class="sourceLineNo">461</span>                };<a name="line.461"></a>
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<span class="sourceLineNo">463</span><a name="line.463"></a>
<span class="sourceLineNo">464</span>        /**<a name="line.464"></a>
<span class="sourceLineNo">465</span>         * Decorates the specified {@code PeekingIterator} to prevent<a name="line.465"></a>
<span class="sourceLineNo">466</span>         * {@code remove()}.<a name="line.466"></a>
<span class="sourceLineNo">467</span>         * <a name="line.467"></a>
<span class="sourceLineNo">468</span>         * @param peekingIterator<a name="line.468"></a>
<span class="sourceLineNo">469</span>         *            the underlying {@code PeekingIterator}<a name="line.469"></a>
<span class="sourceLineNo">470</span>         * @return an unmodifiable view of {@code peekingIterator}<a name="line.470"></a>
<span class="sourceLineNo">471</span>         */<a name="line.471"></a>
<span class="sourceLineNo">472</span>        public static &lt;E&gt; UnmodifiablePeekingIterator&lt;E&gt; unmodifiable(<a name="line.472"></a>
<span class="sourceLineNo">473</span>                        final PeekingIterator&lt;? extends E&gt; peekingIterator) {<a name="line.473"></a>
<span class="sourceLineNo">474</span>                checkNotNull(peekingIterator);<a name="line.474"></a>
<span class="sourceLineNo">475</span>                return new UnmodifiablePeekingIterator&lt;E&gt;() {<a name="line.475"></a>
<span class="sourceLineNo">476</span>                        @SuppressWarnings("unchecked")<a name="line.476"></a>
<span class="sourceLineNo">477</span>                        @Override<a name="line.477"></a>
<span class="sourceLineNo">478</span>                        protected PeekingIterator&lt;E&gt; delegate() {<a name="line.478"></a>
<span class="sourceLineNo">479</span>                                return (PeekingIterator&lt;E&gt;) peekingIterator;<a name="line.479"></a>
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<span class="sourceLineNo">481</span>                };<a name="line.481"></a>
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<span class="sourceLineNo">483</span><a name="line.483"></a>
<span class="sourceLineNo">484</span>        private static class EmptyListIterator&lt;E&gt; implements ListIterator&lt;E&gt; {<a name="line.484"></a>
<span class="sourceLineNo">485</span><a name="line.485"></a>
<span class="sourceLineNo">486</span>                @Override<a name="line.486"></a>
<span class="sourceLineNo">487</span>                public boolean hasNext() {<a name="line.487"></a>
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<span class="sourceLineNo">490</span><a name="line.490"></a>
<span class="sourceLineNo">491</span>                @Override<a name="line.491"></a>
<span class="sourceLineNo">492</span>                public boolean hasPrevious() {<a name="line.492"></a>
<span class="sourceLineNo">493</span>                        return false;<a name="line.493"></a>
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<span class="sourceLineNo">495</span><a name="line.495"></a>
<span class="sourceLineNo">496</span>                @Override<a name="line.496"></a>
<span class="sourceLineNo">497</span>                public E next() {<a name="line.497"></a>
<span class="sourceLineNo">498</span>                        throw new NoSuchElementException();<a name="line.498"></a>
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<span class="sourceLineNo">500</span><a name="line.500"></a>
<span class="sourceLineNo">501</span>                @Override<a name="line.501"></a>
<span class="sourceLineNo">502</span>                public int nextIndex() {<a name="line.502"></a>
<span class="sourceLineNo">503</span>                        return 0;<a name="line.503"></a>
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<span class="sourceLineNo">505</span><a name="line.505"></a>
<span class="sourceLineNo">506</span>                @Override<a name="line.506"></a>
<span class="sourceLineNo">507</span>                public E previous() {<a name="line.507"></a>
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<span class="sourceLineNo">511</span>                @Override<a name="line.511"></a>
<span class="sourceLineNo">512</span>                public int previousIndex() {<a name="line.512"></a>
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<span class="sourceLineNo">515</span><a name="line.515"></a>
<span class="sourceLineNo">516</span>                @Override<a name="line.516"></a>
<span class="sourceLineNo">517</span>                public final void remove() {<a name="line.517"></a>
<span class="sourceLineNo">518</span>                        throw new IllegalStateException();<a name="line.518"></a>
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<span class="sourceLineNo">520</span><a name="line.520"></a>
<span class="sourceLineNo">521</span>                @Override<a name="line.521"></a>
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<span class="sourceLineNo">534</span>                @Override<a name="line.534"></a>
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<span class="sourceLineNo">550</span>                public final void remove() {<a name="line.550"></a>
<span class="sourceLineNo">551</span>                        throw new IllegalStateException();<a name="line.551"></a>
<span class="sourceLineNo">552</span>                }<a name="line.552"></a>
<span class="sourceLineNo">553</span>        }<a name="line.553"></a>
<span class="sourceLineNo">554</span><a name="line.554"></a>
<span class="sourceLineNo">555</span>}<a name="line.555"></a>




























































</pre>
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